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JavaScript, by contrast, doesn't have arrays - it just has objects, which can have numerical keys. a = [] a.foo = 'bar' // works! b = {} b[0] = 42 //

JavaScript, by contrast, doesn't have arrays - it just has objects, which can have numerical keys. a = [] a.foo = 'bar' // works! b = {} b[0] = 42 // also works! I happen to think these designs are both INSANE, but even if you like them, PHP has no advantage here.

uryga 7y ago
so isn't it like PHP, which doesn't have lists, only maps with integer keys?
- azernik 7y ago
  With the exception that unlike (I think?) PHP, JS also uses maps (w hich can only have string keys [1]) to implement objects and classes. Hence their being called objects, not maps. [1] So how do arrays have numerical keys? Well... actually they don't. I was trying to make JS look better than it is in my original comment. Actually, array keys are stringified versions of numbers, and values are automatically cast to string when you put them in indexing braces. Object.keys([1, 2]) --> ["0", "1"] As you can imagine, this leads to gotchas when you assume that a JS object can have, say, a date as a key b = {}; b[new Date()] = 10; Object.keys(b) --> [ "Sat Nov 09 2019 23:15:58 GMT-0800 (Pacific Standard Time)" ]
roblabla 7y ago
I’m pretty sure this is wrong. JS objects and arrays are different. The former will only yield elements from the array itself when iterated on, and has a consistent iteration order, while the later does not.
- mncharity 7y ago
  https://www.ecma-international.org/ecma-262/#sec-array-exotic-objects https://www.ecma-international.org/ecma-262/#sec-array-exoti...
- TurningCanadian 7y ago
  Order is consistent in both https://www.stefanjudis.com/today-i-learned/property-order-is-predictable-in-javascript-objects-since-es2015/ https://www.stefanjudis.com/today-i-learned/property-order-i...
- cutler 7y ago
  JS arrays are array-like objects. That's the official line anyway.
- azernik 7y ago
  That's because arrays happen to override the special [Symbol.iterator] method: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/@@iterator https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... Arrays are objects of class Array which have special literals, override the toString() method, and update the non-enumerable "length" property on certain operations. Try calling Object.keys([1, 2, 3]), or even better try Object.getOwnPropertyNames([1, 2, 3])

uryga 7y ago

so isn't it like PHP, which doesn't have lists, only maps with integer keys?

azernik 7y ago
With the exception that unlike (I think?) PHP, JS also uses maps (w hich can only have string keys [1]) to implement objects and classes. Hence their being called objects, not maps. [1] So how do arrays have numerical keys? Well... actually they don't. I was trying to make JS look better than it is in my original comment. Actually, array keys are stringified versions of numbers, and values are automatically cast to string when you put them in indexing braces. Object.keys([1, 2]) --> ["0", "1"] As you can imagine, this leads to gotchas when you assume that a JS object can have, say, a date as a key b = {}; b[new Date()] = 10; Object.keys(b) --> [ "Sat Nov 09 2019 23:15:58 GMT-0800 (Pacific Standard Time)" ]

roblabla 7y ago

I’m pretty sure this is wrong. JS objects and arrays are different. The former will only yield elements from the array itself when iterated on, and has a consistent iteration order, while the later does not.

mncharity 7y ago
https://www.ecma-international.org/ecma-262/#sec-array-exotic-objects https://www.ecma-international.org/ecma-262/#sec-array-exoti...
TurningCanadian 7y ago
Order is consistent in both https://www.stefanjudis.com/today-i-learned/property-order-is-predictable-in-javascript-objects-since-es2015/ https://www.stefanjudis.com/today-i-learned/property-order-i...
cutler 7y ago
JS arrays are array-like objects. That's the official line anyway.
azernik 7y ago
That's because arrays happen to override the special [Symbol.iterator] method: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/@@iterator https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... Arrays are objects of class Array which have special literals, override the toString() method, and update the non-enumerable "length" property on certain operations. Try calling Object.keys([1, 2, 3]), or even better try Object.getOwnPropertyNames([1, 2, 3])